Abstract: Four scries of macromolocular drugs covalently. linked 5-fluorouracil(5-FU) are synthesized by the use of soluble starch and carboxylmcthylccllulose as carries, and two new 5-FUderivatives by the use of molecular sieve as catalyst. Their structure arc determined by R, ¹HNMR and mass spectra. The changes for the nitrogen content of polymeric drugs with reactions and the influence of the Ncontent on their limiting viscosily arc studied. The hydrolysis delivery of 5-FUfrom starch and carboxymethyl-cellulose derivatives in various of buffer arc researched by moulding physiologicaly acid-alkali enviroment. In addition, antican-car activity (in vivo and in vitro) of some starch derivative has been prelimina-ryly observed.